Open Source Physics Website:
http://www.compadre.org/osp/index.cfm

Phet simulations:
http://phet.colorado.edu/index.php

Applets for Physics:

Waves:
Ripple tank applet.

A fun flash game that gives a sense of gravitational effects:
http://www.thecleverest.com/animated/147

Videos and Resources:

Nova's "The Elegant Universe" - String Theory - related articles and interactive links
http://www.pbs.org/wgbh/nova/elegant/

Physics Courses, Textbooks (free!) and Software online
http://www.lightandmatter.com/

Time dilation experiment You Tube
http://www.youtube.com/watch?v=gdRmCqylsME

Interactive site for easy to learn relativity
http://onestick.com/relativity/